#include <iostream>
using namespace std;

const int N = 30;
int arr[N];
int n, m; 

int main()
{
	while (cin >> n)
	{
		int i = 0;
		for (i = 0; i < n; i++)
		{
			cin >> arr[i];
		}
		cin >> m;
		for (i = 0; i < n; i++)
		{
			if (m == arr[i])
			{
				cout << i << endl; 
				break; 
			}	
		}
		if (i == n)
			cout << "No" << endl;
	}
	
	return 0;
}
